For many people, the word “prefab” suggests standardized structures with little pizazz—functional, but unlikely to garner a second glance. That’s far from the case with today’s modern, green modulars: a diverse array of attractive, durable, eco-friendly products are being combined to create unique, livable, high-performance homes that fit the landscape.

Most prefab designs lend themselves to some modification so customers can customize a plan to accommodate a challenging building site, change window placement for better solar gain, or even add an office annex.

Here are some of the companies across the country that are pushing the envelope on green prefab.